Transparent and conductive metal oxides and doped metal oxides coatings, and specifically tin oxide coatings, are receiving considerable scientific attention for use in solar cells, sensors, smart (heated) windows and touch panel displays, voltage dependent resistors and LED devices, and catalysts.
Diverse methods for particle and nanoparticle metal oxide formation and surface coatings are known in the art. Classification of the wet (doped as well as undoped) tin oxide coating methods reveals that they are mostly produced in acidic media, usually from chloro or alkoxy precursors (followed by an annealing step) [see, for example, Santilli, C. V. et al (Phys. Review B 2007, 75, 205335), Hu, P. W. et al (Appl. Clay Sci. 2010, 48, 368) and Nutz, T. et al (J. Phys. Chem. B 2000, 104, 8430)], made by electroless deposition (e.g. with silver seeding), or are made of preformed, stabilized nanocrystalline dispersions [see Muller, V. et al (Small 2010, 6, 633)]. Much of the antimony tin oxide synthesis efforts are directed towards finding appropriate organic ligands that will control the hydrolysis and condensation rates of the dopant and tin precursors in order to allow intimate contact of the antimony and tin oxides already at the (nanoparticle) dispersion state.
The preparation of tin oxide nanoparticles and hollow spheres from hydroxostannate were described, for example, by Juttukonda, V. et al (J. Am. Chem. Soc. 2006, 128, 420), Urade, V. N. et al (J. Phys. Chem. B 2005, 109, 10538) and Lou, X. W. et al (Adv. Mater. 2006, 18, 2325). Sladkevich, S. et al (J. Sol Gel Sci. Technol. 2009, 50, 229-240) describe the formation of peroxystannate nanoparticles by hydrogen peroxide induced polymerization in water-potassium hexahydroxystannate solutions but did not mention film formation from such solutions. Tolstoy, V. P. (Thin Solid Films 1997, 307, 10-13; Zh Neorg. Khim. 7 (1993) 1146-1148) described a process for synthesizing tin oxide coatings by consecutive oxidation and hydrolysis of tin(II) fluoride by hydrogen peroxide under near-neutral or acidic conditions.